In 2009, the American Recovery and Reinvestment Act authorized an extension of the residential and commercial investment tax credits (ITC) for renewable energy installations.  Taxpayers can claim a credit of 30% of the installed costs of renewable energy systems.  Through the end of 2010, businesses can elect to take the 30% ITC as a grant, payable by the U.S. Treasury Department.  Businesses can also take advantage of the Modified Accelerated Cost Recovery System (MACRS) provisions in the U.S. tax code which authorizes owners to depreciate solar electric and solar thermal systems on a five-year schedule.

Many states and utilities also offer incentives that can be taken in conjunction with federal incentives.  There is an up-to-date database of available incentives and solar-friendly policies, searchable by state, at www.dsireusa.org.